Spinal Cord Tumors:

 
Dr. A. Vincent Thamburaj,   
Neurosurgeon, Apollo Hospitals,  Chennai , India.

Available data regarding epidemiology are limited and they are less common than the intracranial tumors (about 1:10). In most series, the average age at diagnosis is 40 years, ranging between 11 days & 74 years. Both sexes are equally involved. More than 70% of the tumors were located in the thoracic part or cervical (in that order) of the spinal cord.

 

It is convenient to classify the spinal cord tumors by their location within the spinal cord,

as extramedullary intradural, intramedullary, and extradural. 

Although the extradural tumors do not come under spinal cord tumors, it is discussed here briefly.

 

a) Extramedullary intradural tumors are the commonest spinal cord tumor (84% of all intradural tumors). Neurofibromas(29%) and meningiomas(25%) are the common ones. Meningiomas are more common in middle aged women and in the thoracic region. Exophytic ependymomas and astrocytomas account for about 20%. Sarcomas, vascular tumors, epidermoids, lipomas etc are occasionally encountered. 

 

b) Intramedullary tumors are the commonest spinal cord tumors in children. Gliomas (mainly ependymomas & astrocytomass) make up almost 70% of all intramedullary tumors. In children astrocytomas are most frequently encountered, in some material representing up to 81% of such tumors, while in adults alone ependymomas may account for up to 56% of all intramedullary tumors. Vascular tumors, represented by hemaingioblastomas and cavernomas, add upto almost 15% of all intramedullary tumors. Among the other tumors are found cases of subependymomas, sarcoidosis, neurofibromas, ganglioglioma, gangliocytoma, oligodendroma and astrogliosis. In the literature there have also been case reports on primary malignant lymphomas and neurocytomas in the spinal cord.

Occasionally, malignant tumors from the brain, such as medulloblastoms,  may seed.

c) Extradural tumors are mostly metastatic. They spread into spinal cord from contiguous structures. About 5% of all patients with cancer develop vertebral metastasis. Lately,  primary non osseous lymphomas are being reported increasingly.

Bony tumors can be divided into two groups: primary, i.e. arising within the bone, and secondary, i.e. metastatic to bone.  Within the group of primary bone tumors are both benign and malignant forms. 

Benign tumors are predominantly aneurismal bone cysts and osteoblstomas, whereas malignant forms include Ewing’s sarcoma, chordomas, chondrosarcomas, and mesenchymal chondrosarcomas.

 

Pathophysiology:

D7 osteoblastoma

The tumors can cause symptoms due to compression of the cord and interrupting the cord's blood supply. Initially, the veins get compressed, resulting in congestion and edema. Arterial compression occurs later, which may sometimes lead to distant effects; pressure at the D4 and D5 levels may cause a greater deficit because of the watershed area in the vascular supply of the cord at this level.

Direct pressure on the cord and roots leads to disturbed cord function, the long tracts being affected early. Lumbar puncture may sometimes cause a shift in the position of the tumor leading to a sudden increase in the neurological deficit.. In long standing tumors, there may be gliosis, and the recovery following surgery may not be satisfactory.

 

Spinal meningiomas and other tumors do not, in general, differ from their from their intracranial counterparts.

However, gliomas, although share several characteristics with intracranial gliomas, there are some interesting differences.

 

Astrocytomas of the spinal cord are rare neoplasms, about 10 times less common than astrocytomas of the brain. The average age at diagnosis is between 35 and 40 years. Astrocytomas of the spinal cord do not show the correlation between increasing grade and increasing age at diagnosis that is so prominent with cerebral diffuse astrocytomas.

 

Spinal cord astrocytomas are graded according to the same WHO criteria, used for cerebral astrocytomas, and grade is a strong prognostic indicator. Low-grade astrocytomas (WHO grade II/IV) comprise about 75 - 90% of tumors, with the remainder being high-grade astrocytomas (WHO grades III/IV and IV/IV). Tumors typically involve a focal segment of the cord, and have a fairly even incidence along its length, but rarely may involve a large portion of the cord in a condition called "holocord" astrocytoma. The tumor may grow in a diffuse manner with indistinct margins between tumor and the adjacent normal spinal cord tissue, and can extend along spinal nerve roots. Pilocytic astrocytomas have discreet margins.

 

An important feature is the presence of a tumor associated syrinx, which occurs in about 40% of patients with astrocytomas of the spinal cord. Syringes are more common with low-grade than high-grade astrocytomas, are more frequent the further rostral the tumor lies along the cord, and they appear to favor the rostral aspect of cord above the tumor. Syrinx may be less common with astrocytomas than with ependymomas. With respect to syrinx formation, normal CSF flow in the central canal of the cord is disrupted by the presence of the mass lesion. This mechanical explanation probably accounts for the fact that tumor-associated syringes are typically rostral to the tumor.

 

Ependymomas of the spinal cord are slightly more common than spinal cord astrocytomas. The average age of patients is between 35 and 45 years, an age which is higher than for intracranial ependymomas.

 

Spinal ependymomas are thought to arise from ependymal cells lining the central canal. Cellular ependymomas are distributed evenly along the length of the spinal cord, whereas myxopapillary ependymomas occur almost exclusively at the filum terminale and occasionally the conus medullaris. Tumors may extend over several spinal segments, and may have a substantial exophytic component. Holocord lesions are rare. Syringes or tumor-related cysts may be more common with ependymomas than with astrocytomas of the spinal cord. The lesions are usually well circumscribed.

 

Histopathological classification includes myxopapillary ependymoma (WHO grade I/IV), ependymoma (WHO grade II/IV) and anaplastic ependymoma (WHO grade III/IV). The two low-grade lesions are more common than anaplastic ependymoma. Anaplastic ependymomas may be associated with leptomeningeal spread, although this complication occurs with the lower grade lesions as well. Ependymomas, including those arising from the spinal cord, have the unusual propensity to spread outside of the neuraxis. This is particularly true for subcutaneous myxopapillary tumors that arise over the sacrococcygeal region. Metastasis to lung, skin and kidney have been documented.

 

Low-grade ependymomas of the spinal cord are usually slowly growing lesions with little tendency to undergo anaplastic progression to higher grades of histology or more aggressive biological behavior.

 

Clinical features: 

 

Spinal cord tumors produce symptoms due to compression of nerve root or cord, and ischemia vascular compression.

Tethering of the cord by the dentate ligaments and filum terminale may result when expanding lesions oppose this resistance.

The main symptoms are, pain, weakness, sensory disturbance, and autonomic disturbances. In addition, there may be a vertebral deformity, especially in children.

 

Extradural tumors mimic the commoner extramedullary tumors; the root pain is well defined. The pain is aggravated by coughing and sneezing and other spinal movements. Autonomic disturbance is rare, unless it is a rapidly progressive lesion, such as, metastasis.

 

Extramedullary tumors grow in relation to a nerve root. Chronic progressive radicular pain, especially at night, may precede all other symptoms. The combination of  pain associated with  myelopathy can progress for a long time by the patients' ability to cope. Autonomic symptoms are delayed as the center of the cord is involved late unlike the intramedullary tumors. Radicular pain may simulate an angina at times.

 

Intramedullary tumors infrequently progress slowly, & for a long time often with rather mild symptoms and ill-defined pain. The mean distribution of symptoms prior to operation are more than 4-5 years, ranging between 3 months & 11 years. Since these tumors often destroy structures near the centre of the spinal cord, the crossing pain and temperature fibers are frequently damaged and there is early involvement of bladder fibres. In the classical case the tumor therefore presents with an early segmental differential sensory deficit, later followed by long tract signs, with subsequent weakness & wasting of musculature in the extremities. However, the presenting symptoms do not necessarily suggest an intramedullary process. Different degrees of paraesthesias, sensory loss, motor deficits and atrophy of the extremity musculature atrophy are then also encountered.

 

In children muscular weakness with gait disturbances, back or extremity pain and urinary dysfunction are the most common presenting symptoms. Up to 30% of the pediatric patients present as spinal deformities. Spinal deformities, such as kyphosis or scoliosis, when associated with pain often can be warning signs of a spinal cord tumor. 

Congenital lesions are often signaled by mid-lying cutaneous markers such as hemangiomas, a dural sinus tract, etc.  Meningiomas, schwannomas, and neurofibromas can be suggested by other neurocutaneous findings.

 

Signs and symptoms with relation to site:

 

Spinal cord

Conus medullaris

Cauda equina

Weakness

Symmetrical; profound

Symmetrical; variable

Asymmetrical; may be mild

Tendon reflexes

Increased

Increased AJ, decreased KJ

Decreased; asymmetrical

Plantars

Extensor

variable

Flexor

Sensory loss

Symmetrical; sensory level

Symmetrical, saddle anesthesia

Asymmetrical; radicular

Micturition

Spared until late

Early involvement

May be spared

Progression

Rapid

Variable; may be rapid

Variable; may be slow.

An isolated conus tumor is not seen in practice, and at presentation, it usually compresses the roots of cauda equina, and presents as mixed or a cauda equina type of syndrome.

 

Diagnosis:

 

Despite today's advanced imaging, it is vital to ascertain the site of the lesion before requesting an investigation.

It must be remembered that the spinal cord is much shorter than the vertebral column and ends at the lower border of the L1 vertebral body. Hence, the spinal cord segments are not situated opposite the corresponding vertebrae.

There is a progressive increase in the difference between the cord segments and vertebral bodies from above downwards.

The 8 cervical segments extend from the foramen magnum to the upper C7 vertebral body.

The 12 dorsal cord segments lie opposite the D1 to the lower body of D9.

The D4, D8, and the D12 cord segments lie opposite the D3, D6, and D9 vertebral bodies, respectively.

The lumbar cord segments are opposite the D10, D11, and D12 vertebral bodies.

The sacral and coccygeal segments therefore, lie opposite the L1 body. 

 

Plain x-rays:

X-rays may alert a clinician. A widened spinal canal (intramedullary tumor), bony changes (extradural and extramedullary-intradural), and widened intervertebral foramen (neurofibroma) warrant a further imaging. Paravertebral shadows may suggest a malignancy.

 

Myelography:

The classical diagnostic tool was myelography.

With an intramedullary tumor almost invariably showing up as a widening of the cord shadow.

A  filling defect displacing the cord to one side is characteristic of extramedullary lesion.

Serrated or brushlike transverse filling defect suggests an extradural pathology.  

 

MRI:

Magnetic resonance imaging (MRI) is the most useful radiological study for evaluating the spinal canal and its contents and is the imaging of choice.  It is useful both in defining the extent of disease and the possible pathology involved and in evaluating the spinal cord and its surrounding structures in multiple projections. 

 

CT:

CT myelography is useful, when MRI is not possible. The computed tomography (CT) scan is useful in particular for defining bony abnormalities.  CT scanning tends to offer very little insight into intramedullary disease by itself.  Its delineation of soft tissue changes is vastly inferior to that noted by the MRI scan.  Occasionally, CT is combined with myelography, but usually this does not give as clear an evaluation as that given by MRI. 

 

MRI-intramedullary lipoma

 MRI-C1 extramedullary schwanoma

 MRI-C1extramedullary schwanoma

 MRI-dumb bell neurofibroma

MRI-Foramen Magnum    meningioma

 MRI-intradural hemangioblastoma

  

 MRI-holocord

 MRI-intramedullary ependymoma

MRI-intramedullary astrocytoma

Treatment: 

 

Surgical excision is the treatment for extramedullary tumors. Total excision along with involved dura in case of meningiomas is possible and recommended. Sacrificing the nerve root during total excision of neuromas may be justified.

 

The traditional treatment of intramedullary gliomas has been biopsy followed by radiation therapy. However more & more neurosurgeons have changed to aggressive treatment of these neoplasms. The major reasons for this are the diagnostic and operative technical developments that have taken place for the last few years. Thus, MRI increases the accuracy of the diagnosis, and together with perioperative ultrasonography it allows an exposure that minimizes bone removal while maximizing tumor accessibility. the operative microscope and bipolar coagulation marked the  dawn of modern treatment of these lesions, & the introduction of ultrasonic aspiration and surgical laser dramatically modified the strategy in favor of aggressive surgical treatment. 

 

In experienced hands radical resection of ependymomas is now possible, with good functional results. The same is true for haemangioblastomas and cavernomas. Because of their clear demarcation ependymomas and vascular tumors often can & should be totally resected, without risk of increased morbidity.

 

With regards to malignant astrocytomas most surgeons agree that surgery has only little impact on the clinical course. A less radical intervention, to secure minimal surgical morbidity is therefore usually recommended.

 

The surgical treatment of low grade astrocytomas is a bit more controversial, with some authors advocating radical removal of the tumor while others claim that total removal does not yield better outcome compared to less aggressive resection.

 

Symptomatic syrinx must be drained.

 

Post operative deformity, subluxation and instability is reportedly common following extensive laminectomy in the young (under 18yrs of age), especially in the cervical region. Reportedly, laminoplasty can prevent a deformity.

Some advise stabilization procedure as preventive measure. Most surgeons advise a close follow up.

 

Radiation therapy for intramedullary tumors has been controversial during the last decade. Clearly, radiation is accompanied by a risk of spinal injury the functional tolerance of the cord being 10 – 15% lower than that of the brain. Radiation sensitivity increases with the length of the cord irradiated, the size of the daily dose, and the total dose given. A total dose of 5000 rads given in 25 fractions over 5 weeks is usually considered acceptable.

Almost all studies support no indication for post operative irradiation for intramedullary ependymomas and low grade astrocytomas.

With regards to high grade gliomas, for clinically progressive lesions, and for tumors in which a substantial resection cannot be achieved, most surgeons still agree that radiation therapy is to be recommended, although with uncertain results. Craniospinal irradiation is recommended for high grade ependymomas due to the higher risk of tumor growth in the CSF pathways.

 

Radiotherapy is clearly of value in metastatic lesions.

 

Chemotherapy can be considered in patients with progression of disease after radiation therapy. There are a number of case reports and small series indicating chemotherapy responses in pediatric and adult spinal cord astrocytomas. Although astrocytomas of the cerebral hemispheres are not highly responsive to chemotherapy, recent evidence has suggested that astrocytomas with 1p loss may also be sensitive to chemotherapy.

Chemotherapy can also be administered in ependymomas with progression of disease after radiation therapy, since ependymomas demonstrate some responsiveness to chemotherapy.

 

Prognosis: 

 

The prognosis for extramedullary intradural tumors is good following a total excision.

 

The reported results of treatment of intramedullary tumors are still difficult to interpret and evaluate because of heterogenous management strategies, small number of patients and short periods of follow up. Clearly, most patients experience some neurological morbidity in the immediate post operative period, deficits which in benign lesions may improve within 3-6 months.

Studies suggest that the surgical outcome at follow up is directly related to the patients’ pre operative status. Thus recovery from a significant & long standing deficit rarely occurs. 

 

Prognostic factors for patients with spinal cord gliomas include histological grade and duration of symptoms prior to diagnosis.

Recurrence is almost always due to tumor growth at the original tumor site, although the possibility of simultaneous tumor dissemination throughout the neuraxis should be also considered, especially with high-grade tumors.

 

At present malignant astrocytomas of the spinal cord are incurable lesions with a behavior that is very similar to that of the histologically identical lesions found in the brain. Thus although operation may result in palliation, malignant astrocytomas usually recur within a year, with a fatal outcome in less than 2 years after operation. The overall 5-year survival for patients 30% with high-grade tumors.

The prognosis of low grade astrocytomas is of course better, with some claims of an excellent long term prognosis. Most surgeons are more guarded. The overall 5-year survival is 70-90%.

 

The outcome following surgery of intramedullary ependymomas is more gratifying. Radical removal can usually be achieved, and if so tumor recurrence is very unusual. Overall survival of series of patients with low-grade ependymomas of spinal cord are in the range of 85% 5-year survival. Survival rates are even higher in patients with myxopapillary ependymomas and are significantly lower in patients with anaplastic ependymomas.

 
 

 

 

 

 

 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 

 

 

 

 

 

 


 

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